1. Field of the Invention
The present invention relates to a positioning apparatus to properly position a thin plate material and a pressing apparatus to properly position and press a thin plate material.
2. Description of Related Art
A hard disk drive installed in, for example, a computer has a head suspension to write and read data to and from a disk in the hard disk drive. The head suspension has a thin load beam provided with a head that is positioned at high speed to a target spot on the disk. The load beam must be light, stiff, nonmagnetic, and resilient. For this, the load beam is formed by bending, punching, and cutting a thin plate material made of stainless steel.
The load beam is made thinner year by year from 0.100 mm to 0.050 mm, 0.030 mm, 0.025 mm, and the like. Such a thin plate material is precisely bent and formed into the load beam having required functions and rigidity balance.
To produce the precision load beam, a thin plate material must accurately be positioned. For example, to provide the load beam with a dimple, which enables a slider attached to the load beam to perform gimbal motion, the thin plate material must be positioned at a center position accuracy of ±0.01 mm or smaller (Cpk>1.5) in an in-plane direction. Thereafter, the thin plate material is pressed into the load beam having the dimple.
When positioning and pressing a thin plate material, positioning pins and holes are used. Use of the positioning pins and holes puts a limit on a positioning accuracy because the positioning pin usually has a straight part that engages with the positioning hole with a clearance being left between them.
To solve this problem, there are related arts disclosed in Japanese Unexamined Patent Application Publications No. H07-52096 (hereinafter referred to as Patent Document 1) and No. H11-330336 (hereinafter referred to as Patent Document 2).
According to the related art of Patent Document 1, a plate material has a positioning hole into which a positioning pin is inserted. The positioning pin is laterally pushed with a spring, to push an inner side wall of the positioning hole when inserted in the positioning hole, thereby positioning the plate material in an in-plane direction.
When the positioning pin is inserted into the positioning hole of the plate material, a tapered front end of the positioning pin receives force from the inner side wall of the positioning hole, and therefore, the positioning pin moves against the spring. As a result, a straight part of the positioning pin enters into the positioning hole, to position the plate material in an in-plane direction.
Even if there is a clearance between the positioning pin and the positioning hole, the related art of Patent Document 1 properly positions the plate material.
This related art, however, has a risk of deforming the positioning hole with the positioning pin if the plate material is thin because the spring force acts orthogonally to the inserting direction of the positioning pin.
The related art of Patent Document 2 uses a feed pin and positioning pin, so that a tapered part of the positioning pin may engage with a positioning hole of a plate material.
The tapered part of the positioning pin manages a clearance between the positioning pin and the positioning hole, to properly position the plate material.
This related art, however, raises a problem when successively positioning a plurality of thin plate materials at a certain speed. In this condition, the tapered part of the positioning pin hits the positioning hole and deforms the same, to deteriorate positioning accuracy and hinder continuous positioning.
In this way, the related arts of Patent Documents 1 and 2 have limits in speedily and accurately positioning a thin plate material in an in-plane direction by inserting a positioning pin into a positioning hole of the thin plate material.